T-20 date

So, when I bought my 1996 Max IV, it was in pieces. Actually, worse than pieces. One of the previous owners had made it into a hydraulic machine. Then, the owner before me took all of that out. What I bought was a pile of random parts, and an extra Max II tub (original style wheels). It came with a "rebuilt" T-20, which I have since figured out wasn't. My question is, Now can I tell if this is an older style (pre-thrush washer) unit before opening it up. Will I need different internal parts depending on the age of the T20? Does the code stamped on the info plate, which is missing all its writing, tell anything?

The code is 2713.

Thanks
Kevin

After doing some asking around, a kind soul shared with me that my T20 was produced in 1975. That probably means that it is an original Borg Warner unit. I guess I should be running popsicle style levers. The ones that came in the collection of parts were not, and were not in the best shape. Now, I guess I'll know that thrush washers will not be needed.

Popsicle trans have a pin pressed into the case halves between the two plungers otherwise its u channel.